Yep just like the prev post said... even using the same test can take different amounts of time... same goes for how dark the line is... you yourself could take the exact brand of tests at the same time with the same urine and the lines could be different colors... the fact that both you and your friend have different concentrations of urine would affect the speed as well.... only thing that matters is that the line appeared in the allowed amount of time....
Not necessarily as long as the result came back in the time frame the directions said you're good